1. Akiyama, H.: Chinese Rings Book, Shinkigensha (2003) (in Japanese)
2. Akiyama, H.: Picture and Shape Puzzles Book, Shinkigensha (2005) (in Japanese)
3. Caillois, R.: Les jeux et les hommes. Gallimard (1967)
4. Danesi, M.: The Liar Paradox and the Towers of Hanoi. Wiley, Chichester (2004)
5. Higashida, H.: Kyoto University Student, Higashida’s Puzzles. Kadokawa Gakugei Publisher (2010) (in Japanese)